Tension on the tube network threatens to boil over, and security is stepped up. The accidental verdict in the first death is called into question and the witnesses are brought in for interview. Amongst them is Lana Sutherland, a young hotel worker who has taken in a homeless man, Owen. DI Nelson lets Lana slip through the net before he realizes she may be harboring a dangerous killer. Nikki helps Nelson unearth the mystery of his father's death, allowing...

Jack leads the hunt for suspected killer Bruno, the brother of the Polish teenager shot by the armed police, and enters London's small but devastating gun trade.

Disillusioned with her work at MI6, spy Sylvia Fox travels to Italy for the wedding of her niece. Although her relationship with her sister, Isabel, is troubled, Sylvia is welcomed warmly by her family. But when the groom goes missing, leaving a dead woman behind, Sylvia feels compelled to investigate. The trail leads her from an empty pizza box and stolen children's book to a deadly showdown.

The accidental fatal shooting of a Polish teenager in an armed police operation triggers a series of murders that link Turkish gangsters, a grieving family and a fractured firearms unit.

Nikki's suspicions over David Cannon are further aroused when she discovers blood in the boot of his car. With Thomas' support, she takes samples to test for DNA. Does it belong to Sally Vaughn?

When suspected pedophile Dale Barge is found murdered in a children's playground, Nikki and Jack are brought in by inexperienced detective Rory Drennan. It's not long before the team link Barge's death to a missing child, Lizzie Craddock. Jack teams up with Child Protection DI, hard-nosed Gina Conroy. They put pressure on Lizzie's parents, Johnnie and Cheryl, to try to find her. Lizzie's social worker Louise is brought in to help, and Nikki encourages...

Nikki is under fire for leaking information on a suspect, and Thomas is called in to play peacemaker. Jack and DI Ashton track down the mystery witness. Before the killer strikes again, the team must uncover the true story of Ruth Tresize's disappearance three years earlier.

An ex-convict is killed and suspicion lands on a recently released child killer. As other former long-term prisoners out on a life license come under scrutiny, the team learns how fragile their freedom is.

Daniel Garvey is found dead in his car and social worker Louise fears that he may have been killed by his sixteen-year-old stepson Kevin, who has just come out of care. Nikki, Jack and Thomas focus in on Lizzie Craddock's movements on the night of Barge's murder. Jack and DI Gina Conroy discover Lizzie's last known location, but fear what they may find there. Louise comes under further pressure when she is forced to make a call on whether a sick child,...

A family murdered at a picnic leads the team to the female victim's estranged husband. But all is not what it seems, and Nikki and Jack are thrown into mortal danger.